Direct Measurement of Ion Diffusivity in Oxide Thin Film by Using Isotope Tracers and Secondary Ion Mass Spectrometry

Abstract

Diffusion of oxide ions along heterostructured yttria-stabilized zirconia (YSZ) epitaxially grown on single crystalline MgO (001) is investigated. Pulsed laser deposition is used for the epitaxial growth and focused ion beam was applied to open the lateral surface of the YSZ-MgO interface layers and to enable incorporation and diffusion of oxygen. The sample is annealed in O-18(2) environment to trace oxide ion transport with Al2O3 layers atop to block diffusion perpendicular to surface of the YSZ plane. Time-of-flight secondary mass ion spectrometry (TOF-SIMS) analyze the planar diffusion profiles. Diffusivity and surface exchange rate are estimated by SIMS data fitting. As a result, it is identified that both oxide ion diffusion and surface incorporation rates are significantly enhanced on surface of the heterostructured YSZ on MgO (001) compared to bulk YSZ.